In-ground conduit system for geothermal applications

ABSTRACT

An in-ground conduit system for a ground source heat pump is provided. The in-ground conduit system is a conduit-loop having at least one wing member mounted on the conduit loop such that the wing member contacts the ground in such a way so as to resist upward movement of the conduit loop.

BACKGROUND OF THE INVENTION

The invention relates generally to the field of geothermal heating andair conditioning systems and in particularly to pipe systems used forin-ground heat exchange. The invention provides a system havingin-ground conduit system which is simpler to install than previousconduit systems.

Geothermal heating and air conditioning systems, i.e. heat pump systems,are increasingly popular for efficient heating and cooling of loads, forexample as part of a heating-ventilation-air conditioning (HVAC) systemfor buildings. Heat pump systems generally include heat exchangersthermally coupled to the load and to a heat source or heat sink, theheat exchangers being connected in a refrigerant or coolant loop whichincludes a compressor and an expander. The compressor raises thepressure (and therefore the temperature) of the refrigerant and theexpander lowers the pressure, producing a lower temperature in therefrigerant.

In heating a load, a "ground source" heat pump, which has thesource/sink heat exchanger thermally conductively coupled to the ground,can extract a virtually limitless supply of thermal energy from theearth and transfer the energy to the load. A heat pump cools a load byextracting thermal energy from the load and transferring it to the earthfor dissipation therein. In this manner the ground functions as either aheat sink or heat source. Modern day heat pumps for HVAC systems areequipped with reversing features such as valves to arrange the flow ofrefrigerant so that they may both heat and cool the load, as needed.

A ground source heat pump requires a subterranean heat exchanger. Whileit is possible to use intermediate heat exchangers for transferring heatthrough thermally coupled fluid flow paths or the like, preferably therefrigerant or coolant is pumped through the pipes by the compressor andserves directly as the carrier for conveying the thermal energy to orfrom the ground. Thus, extra heat transfer losses, such as thoseinherent in ground water source systems, are avoided. The coolant isrelatively heated by compression and cooled by expansion, leading to therespective heat exchangers, thereby raising the temperature of the hotside heat exchanger above the temperature of the load and lowering thetemperature of the cool side heat exchanger below the temperature of thesource, whereupon heat transfer occurs. Compression and expansionnormally include a change of state of the coolant between liquid andgaseous states.

The load heat exchanger is typically above ground and the ground heatexchanger is preferably well below the surface of the ground. Connectingpipes for the ground heat exchanger, and the pipes defined by the heatexchanger itself, can be horizontal, vertical or slanted. A typicalinstallation may include combinations of these orientations, dependingupon particular design criteria. The problem encountered in theinstallation of the pipes, particularly in a vertical or slantedorientation, is the tendency of the pipe to rise upward in the verticalor slanted hole after installation.

Generally, in installation of the slanted or vertical pipe, a bore-holeis drilled and a double run of pipe connected by a U-bend fitting isinserted into the bore-hole. The pipe is usually inserted into thebore-hole by utilizing weights attached to the U-bend fitting to forcethe pipe into the hole. After the pipe is inserted, the weights areusually retrieved using a line attached to the weights. However, whenthe steel bars used for weights to force the piping into the well areretrieved, the piping has a tendency to come out of the well with theweights.

It would be advantageous to have a low cost method of resolving theforegoing problem.

SUMMARY OF THE INVENTION

It is an object of this invention to provide an in-ground conduit systemwhich can have a vertical or slanted orientation and avoid the problemof the conduit system moving upward in the vertical or slanted hole.

In accordance with the present invention, there is provided an ingroundconduit system for a ground source heat pump comprising at least oneconduit loop having two substantially parallel members connected by aU-shaped pipe member having a vertex and further comprising at least onewing member mounted on the conduit loop at or near the vertex such thatthe wing member contacts the ground in such a way as to resist upwardmovement of the conduit loop.

In accordance with another aspect of the present invention, there isprovided a method of preventing a pipe conduit loop from moving upwardin a bore-hole. This is achieved by attaching at least one wing memberto the pipe such that the wing member extends out from the pipe suchthat in lowering the pipe into the bore-hole the wing member pointsgenerally upward so that the wing member will allow the pipe to belowered into the bore-hole but will contact the ground so as to resistupward movement of the pipe.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a simplified illustration of a geothermal heat pump systemutilizing a vertical in-ground conduit system.

FIG. 2 is an isometric illustration of a U-bend fitting for an in-groundconduit system having two wing members.

FIG. 3 is an elevation view of the embodiment illustrated in FIG. 2.

FIG. 4 is a section taken along line 4--4 of the embodiment of FIG. 3.

FIG. 5 is an illustration of the use of the embodiment of FIGS. 2-4.

FIG. 6 is an illustration of an alternate embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With continuing attention to the drawings wherein applied referencenumerals indicate parts similarly hereinafter identified, FIG. 1illustrates a geothermal heat pump system utilizing a vertical in-groundconduit system. Heat exchange fluid circulating through heat pump 2moves through underground pipe 4, circulates through U-shaped pipe 6,moves up through underground pipe 8 and returns to heat pump 2.Underground pipes 4 and 8, along with U-shaped pipe 6, form in-groundconduit system 3. Typically underground pipes 4 and 8 will be straight,substantially parallel to each other and have a vertical or slantedorientation, preferably a vertical orientation. During the heatingcycle, the heat transfer fluid absorbs heat from the earth 28 during itscirculation through the in-ground conduit system 3 and returns to theheat pump where the heat pump compresses the warm heat transfer fluid toa higher temperature, extracts the heat from it, and distributes theheat extracted through conventional duct systems in the building 10.

During the cooling cycle, heat transfer fluid circulating throughin-ground conduit system 3 ejects heat which is absorbed by the earth28. The cooled heat transfer fluid then returns to the heat pump to pickup more heat removed from the building 10. FIG. 1 illustrates an exampleof a geothermal heat pump system using a single vertical ground loop forsimplicity. However, most systems use more than one vertical loop,usually one loop for each ton of air conditioning capacity is used. Themultiple loops are fused in parallel to a header pipe carrying the heattransfer fluid to and from the building. Alternately, systems can bearranged to use a slanted in-ground conduit system rather than avertical in-ground conduit system.

With both the vertical and slanted in-ground conduit system difficultiesarise installing the pipe because of the tendency of the pipe to moveupward. Typically, this problem is encountered during installation whenthe weights, which were used to place the in-ground conduit system intothe drilled hole, are taken out of the hole. At that time, the pipe hasa tendency to move upward with the weights as they are being removed.

The present invention solves this problem by utilizing wing membersattached to the in-ground conduit system of slanted or vertical pipes.Turning now to FIGS. 2-5, an embodiment of the present inventionutilizing a pair wing members in accordance with the invention can beseen. In FIGS. 2-4, U-bend fitting 12 can be seen. U-bend fitting 12comprises U-shaped pipe 6, mounting bracket 14 and wing members 16 and18.

Mounting bracket 14 has a hole 20 (FIG. 4). The bracket 14 is positionedon U-shaped pipe 6 such that the hole is in the area of the vertex ofthe U-shaped pipe 6. Mounting bracket 14 can be attached to the U-shapedpipe 6 after it has been molded or, preferably, mounting bracket 14 ismolded as an integral part of the U-shaped pipe 6.

Wing members 16 and 18 are formed from a single length of material suchas a suitable relatively small diameter plastic pipe. Although wingmembers 16 and 18 can be formed from any suitable material and can beseparate pieces attached at hole 20, they are illustrated as beingformed from a single length of material, shown as a tube. While thematerial forming wing members 16 and 18 can be any suitable materialwhich is resilient enough to allow the in-ground conduit system to belowered into a well hole and yet strong enough to prevent upwardmovement of the conduit system, as described below, it is presentlypreferred to use polyethylene as the material. The length of material isinserted into hole 20 provided in mounting bracket 14. After the lengthof the material is centered within the hole the length of material isbent until it crimps on both sides of the U-bend. This locks thematerial into mounting bracket 14.

Referring now to FIG. 5, U-bend fitting 12 is attached to undergroundpipe 4 at end 22 of U-shaped pipe 6. Similarly, end 24 of U-shaped pipe6 is connected to underground pipe 8. The U-shaped pipe 6 is connectedto underground pipes 4 and 8 so as to allow fluid flow communicationsuch that the underground pipes along with the U-shaped pipe 6accommodate a continuous loop for the fluid flow.

Wing members 16 and 14 are positioned so that they point outward andupward from in-ground conduit system 3. Thus, when the pipe is beinglowered into hole 26, the wing members will flex upwards to allowin-ground conduit system 3 to enter the hole and be lowered therein.However, when upward pressure is applied, wing members 14 and 16 willcatch on the sides of the bore-hole coming into contact with the ground28 and thus resisting the in-ground conduit system 3 from moving upward.

FIG. 6 illustrates a second embodiment of an apparatus according to theinvention. In FIG. 6, wing members 14 and 16 are mounted ontounderground pipe 4. Wing members 14 and 16 can be mounted onto pipe 4 byany suitable method. Wing members 14 and 16 are positioned so that theyflex toward the conduit loop when in-ground conduit system 3 is beinglowered down into hole 26 and then contact the ground so as to resistupward movement of the pipe.

Changes may be made in the instruction, combination and arrangement ofparts or elements as heretofore set forth in the specification and asshown in the drawings without departing from the spirit and scope of theinvention, as defined in the following claims.

That which is claimed:
 1. An in-ground conduit system for a groundsource heat pump comprising:at least one conduit loop having a firstmember having a first end and a second end, a second member having afirst end and a second end, a U-shaped member having a vertex, a firstend connected in fluid flow communication with said second end of saidfirst member and a second end connected in fluid flow communication withsaid first end of said second member; and at least one wing membermounted on said conduit loop in the area of said vertex of said U-shapedmember such that said wing member is oriented to contact the ground insuch a way as to prevent upward movement of said conduit loop whereinsaid at least one wing member comprises a first wing member and a secondwing member formed from a length of material having a first end portionand a second end portion wherein said length of material is crimped at apoint between said first end portion and said second end portion andwherein the resulting crimped section is mounted in the area of thevertex of said U-shaped member such that said first end portion formssaid first wing member and said second end portion forms said secondwing member.
 2. An in-ground conduit system for a ground source heatpump comprising:at least one conduit loop extending primarily verticallyinto the ground, having a first member having a first end and a secondend, a second member having a first end and a second end, and a U-shapedmember having a first end connected in fluid flow communication withsaid second end of said first member and a second end connected in fluidflow communication with said first end of said second member; and alength of material having a first end portion and a second end portionwherein said material is crimped at a point between said first endportion and said second end portion and wherein the resulting crimpedsection is mounted in the area of the vertex of said U-shaped membersuch that said first end portion forms a first wing member and saidsecond end portion forms a second wing member such that said first wingmember and said second wing member are capable of contacting the groundin such a way as to prevent upward movement of said conduit loop.